1. Field of the Invention
The present invention relates to an information device having a function for inputting information by using means such as a pen. In particular, the present invention relates to an information device in which pen input operations are performed on a screen of a display device. The present invention relates to an EL display device using EL elements as the display device, and further, relates to electronic devices, such as portable information devices, having the information device of the present invention.
Note that, in this specification, the term EL element denotes an EL element utilizing both light emission from singlet excitons (fluorescence) and light emission from triplet excitons (phosphorescence).
2. Description of the Related Art
The demand for pen input method portable information devices has risen in terms of miniaturization and operability. The pen input method is a method for the input of information by using a specialized pen or arbitrary pen, and by either contacting pen tip to a display screen, or bringing the pen tip close to the display screen.
Namely, input of information corresponding to positions indicated by the pen tip on the display screen is performed. The display screen also functions as a pen input screen. It is necessary to specify the positions indicated by the pen on the pen input screen with this pen input method, and methods such as a resistive film method and an optical method exist as means for the pen input.
The resistive film method is explained first.
FIG. 7 is a cross sectional diagram showing the structure of a resistive film pen input device. Note that a pen input device 7711 is formed overlapping with and on the upper portion of a display device 7708. The display device 7708 has a display portion 7709 and a peripheral circuit 7710.
A movable electrode 7701 and a fixed electrode 7702 sandwich dot spacers 7704 in the pen input device 7711, and both are connected in parallel with a gap of approximately 100 to 300 xcexcm by a lamination material 7703. The movable electrode 7701 and the fixed electrode 7702 are formed by conductive materials having transparency so that images projected on the display portion 7709 of the display device 7708 can be seen through the pen input device 7711. In general, an indium tin oxide (ITO) film is used as the conductive material having transparent properties.
The movable electrode 7701 touches the fixed electrode 7702 in a position indicated by the input pen 7704 on the pen input device 7711 with the resistive film method (input point A in FIG. 7). At this time, in the method, the position of the input point A is read out as the ratio of resistances R1 and R2 from two position detection electrodes 7706 and 7707.
Specifically, an example of performing position read out is shown in FIG. 8. A pressure is applied by an input pen 807 from a movable electrode 801 side and there is contact between the movable electrode 801 and a fixed electrode 802 at the input point A. A voltage is applied between two electrodes 803 and 804 of the movable electrode 801 here, and an electric potential gradient is generated within the movable electrode 801. By measuring the electric potential VA of the input point A at this point, resistance values Rx1 and Rx2 from the electrode 803 and the electrode 804 to the input point A can be found. If the film quality of the movable electrode 801 is assumed to be uniform, then the resistance values Rx1 and Rx2 are proportional to the distances from the electrodes 803 and 804 to the input point A, respectively.
Similarly, a voltage is applied between two electrodes 805 and 806 of the fixed electrode 802, and an electric potential gradient within the fixed electrode 802 is generated. By knowing the electric potential VA of the input point A at this point, resistance values Ry1 and Ry2 from the electrode 805 and the electrode 806 to the input point A can be found. If the film quality of the fixed electrode 802 is assumed to be uniform here, then the resistance values Ry1 and Ry2 are proportional to the distances from the electrodes 805 and 806 to the point A, respectively. The position of the input point A can thus be determined.
Note that the method of measuring the electric potential of the input point A for measuring the position of the input point A is not limited to the above structure, and various other methods can also be used.
An optical method pen input device is explained next. A schematic diagram of an upper surface of the optical method pen input device is shown in FIG. 9A.
If a pen tip of an input pen 901 makes contact to an input portion 902, the contact position is detected. The position detection operation is explained.
X-1 light emitting diodes (hereafter referred to as LEDs) 21 to 2x are arranged in a right edge portion in the periphery of the input portion 902, and x-1 phototransistors (hereafter referred to as PTs) 31 to 3x are arranged in a left edge portion of the input portion 902, opposite the LEDs 21 to 2x. The light emitting diodes and the phototransistors are embedded in a frame 4.
Y-1 LEDs 51 to 5y are arranged in a lower edge portion, and y-1 PTs 61 to 6y are arranged in an upper edge portion, opposite the LEDs 51 to 5y. The LEDs and the PTs are embedded in the frame 4.
The LEDs 21 to 2x and the PTs 31 to 3x form x-1 horizontal direction touch input lines, and the LEDs 51 to 5y and the PTs 61 to 6y form y-1 vertical direction touch input lines.
The term touch input lines refer to paths along which light emitted from the LEDs travels when input to the PTs between pairs of opposing LEDs and PTs.
Note that although PTs are used as the components having reference numerals 31 to 3x and 61 to 6y, there is no limitation associated with PTs, and other components can be freely used provided that they are photoelectric conversion elements that convert light into an electric signal.
In order to increase the directionality of light emitted from the LEDs 21 to 2x and 51 to 5x, and made incident on the PTs 31 to 3x and 61 to 6x, hole shaped slits 7 are formed in front of the frame 4 in which each of the elements is embedded.
FIG. 9B is a cross sectional diagram along a line segment axe2x80x94a of FIG. 9A. A display device 910 is formed in a portion below the pen input device. The display device 910 is structured by a display portion 911 and a peripheral circuit 912. Differing from the resistive film method, it is possible to directly see images displayed in the display portion 911.
FIG. 9A is again referenced.
The emission of light and the receiving of light are performed one pair at a time from the edge for the pairs of opposing LEDs and PTs. This operation (hereafter referred to as scanning) is performed at the same time for the horizontal direction touch input lines and the vertical direction touch input lines in the pen input device having the above structure.
One point within the input portion 902 is indicated by the input pen 901. The input point A within FIG. 9A is indicated. Light is cutoff between two touch lines 2n to 3n and 5m to 6m at this point, and the position A at which the input pen 901 contacts is recognized.
It is necessary to mechanically change the shape of the movable electrode as information is input with the resistive film method. The movable electrode thus fatigues with repeated shape change, and there is the possibility of it being broken. This becomes an endurance problem.
Further, even if damage does not reach actual breakage, the ITO film conductivity becomes non-uniform due to repeated deformation and in the case where minute cracks on the order of micrometers in size are formed during manufacturing process. Therefore, problems in the precision of input pen location detection develop.
In addition, the display device image is read out through the two electrodes, the movable electrode and the fixed electrode. The transmittivity of the transparent electrodes is not 100% at this time, and therefore light from the display device is attenuated and brightness of the image falls, generating visibility problems with the screen. The intensity of light emitted form the display device consequently must be made stronger so as to increase the brightness of the image. and there is a problem with increased power consumption of the device.
Further, when stress opposing substrate is applied from the outside of the device, and the distance between the two electrodes, the movable electrode and the fixed electrode, becomes equal to or less than 40 xcexcm, then a problem exists in which Newton rings appear due to an interference effect of light reflected between the two electrodes.
In addition, this is a capacitor structure in which the two electrodes are arranged in parallel, and therefore consumption is large when a battery electric power source is used. This is a large problem for portable information devices in which low power consumption is desired.
On the other hand, there are no mechanical endurance problems with the optical method pen input device because it is not necessary for the thin films to repeatedly be deformed as with the resistive film method. Further, the display device is not seen through transparent electrodes, and therefore problems with screen visibility are also few.
However, for cases where light emitted from the light emitting elements is not received in a straight line by the paired light receiving elements, there is a possibility that recognition will not be made even if the input pen or the like indicates the position.
Furthermore, it is necessary to form columns of light emitting elements and light receiving elements, slits and the like on the display device, and therefore there is a problem in that it is difficult to make the device smaller.
With an information device having a pen input function according to the present invention, both EL (electroluminescence) elements and photoelectric conversion elements are arranged in pixels of a display device, and input of information is performed by a pen reflecting light in a tip of the pen.
EL elements are self light emitting elements, and are mainly used in EL display devices. EL display devices are also referred to as organic EL display devices (organic EL displays, OELDs) and organic light emitting diodes (OLEDs).
The EL element is structured by sandwiching an EL layer between a pair of electrodes (an anode and a cathode). The EL layer normally has a lamination structure. A lamination structure proposed by Tang, et al. of Eastman Kodak Corp. having a hole transporting layer, a light emitting layer, and an electron transporting layer can be typically given. This structure is known to emit light with extremely high efficiency.
Further, other lamination structures may also be formed on the electrode, such as a lamination of a hole injecting layer, a hole transporting layer, a light emitting layer, and an electron transporting layer, and a lamination structure of a hole injecting layer, a hole transporting layer, a light emitting layer, an electron transporting layer, and an electron injecting layer. A material such as a fluorescent pigment may also be doped into the light emitting layer.
The term EL layer indicates all of the layers formed between a pair of electrodes in this specification. The layers such as the hole injecting layer, the hole transporting layer, the light emitting layer, the electron transporting layer, and the electron injecting layer stated above are therefore all contained within the category of EL layers. A predetermined voltage is applied to the above structured EL layers from the pair of electrodes. Recombination of the carrier thus occurs in the light emitting layer, and light is emitted.
Note that the EL layer is not limited to one having a lamination structure in which the layers are clearly separated, such as the hole injecting layer, the hole transporting layer, the light emitting layer, the electron transporting layer, and the electron injecting layer. Namely, the EL layer may also take a structure having a layer in which materials structuring the layers such as the hole injecting layer, the hole transporting layer, the light emitting layer, the electron transporting layer, and the electron injecting layer are mixed.
For example, an EL layer with a structure having a mixed layer between an electron transporting layer and a light emitting layer, the mixed layer structured by a material structuring an electron transporting layer (hereafter referred to as an electron transporting material) and a material structuring a light emitting layer (hereafter referred to as a light emitting material), may also be used.
Note that low molecular weight materials, high molecular weight materials, and intermediate molecular weight materials may all be used for the EL layer.
Note also that, within this specification, the term intermediate molecular weight material indicates a material which does not have sublimation properties and in which the length of molecules linked together is 10 xcexcm or less.
Photodiodes and the like can be used as the photoelectric conversion elements. The term photodiode denotes an element having an anode electrode, a cathode electrode, and a photoelectric conversion layer between the anode electrode and the cathode electrode in this specification.
Note that photodiodes are not limited to this structure, and PIN structure photodiodes having a photoelectric conversion layer constituted of a p-type semiconductor layer, an n-type semiconductor layer and an i-type (intrinsic) semiconductor layer between the p-type semiconductor layer and the n-type semiconductor layer may also be used. Further, a PN type photodiode constituted of a p-type semiconductor layer and an n-type semiconductor layer may also be used.
Furthermore, an element having a photoelectric conversion layer made from an organic compound or the like may also be used as the photoelectric conversion element.
If light is irradiated after applying an inverse bias voltage between the cathode electrode and the anode electrode of a photodiode (hereafter referred to as between the photodiode electrodes), then the voltage between the electrodes is lowered by a carrier developing due to the light. The amount that the voltage drops becomes larger as the intensity of the irradiated light becomes stronger. Light is thus detected as an electric signal by the ratio of the voltage in the case where light is irradiated to the photodiode and the voltage in the case where there is no irradiation of light.
EL elements and photodiodes are formed in a matrix shape on the same substrate, and the operation of each of the EL elements and the photodiodes is controlled by using thin film transistors (TFTs) similarly formed in a matrix shape.
An information device that displays a clear image without losing image brightness and that is excellent in durability, enabling miniaturization, having good precision, and having a low electric power consumption pen input function can thus be obtained.
Structures of the information device of the present invention are stated below.
In accordance with the present invention, there is provided an information device having:
a plurality of pixels; an input pen; and an EL element and a photoelectric conversion element in each of the plurality of pixels; characterized in that:
light emitted from the EL elements is reflected by the input pen; and the light reflected by the input pen performs information input by being input to the photoelectric conversion elements.
The information device may also be characterized in that the EL elements and the photoelectric conversion elements are formed on the same substrate.
The information device may also be characterized in that the photoelectric conversion elements are photodiodes.
In accordance with the present invention, there is provided an information device having:
a plurality of pixels;
an EL display source signal line driver circuit;
an EL display gate signal line driver circuit;
a plurality of EL display source signal lines;
a plurality of EL display gate signal lines;
a plurality of electric power source supply lines; and
an input pen; characterized in that;
the EL display source signal line driver circuit inputs signals to the plurality of EL display source signal lines;
the EL display gate signal line driver circuit inputs signals to the plurality of EL display gate signal lines;
the plurality of pixels each have an EL display portion and a sensor portion;
the EL display portion and the sensor portion are formed on the same substrate;
the EL display portion has a switching TFT, an EL driver TFT, and an EL element;
a gate electrode of the switching TFT is connected to one of the plurality of EL display gate signal lines;
one of a source region and a drain region of the switching TFT is connected to one of the plurality of EL display source signal lines, and the other of the source region and the drain region of the switching TFT is connected to a gate electrode of the EL driver TFT;
one of a source region and a drain region of the EL driver TFT is connected to one of the plurality of electric power source supply lines, and the other of the source region and the drain region of the EL driver TFT is connected to the EL element;
the sensor portion has a photodiode;
light emitted by the EL element is reflected by the input pen; and
input of information is performed in accordance with the light reflected by the input pen being input to the photodiode.
In accordance with the present invention, there is provided an information device having:
plurality of pixels;
a sensor source signal line driver circuit;
a sensor gate signal line driver circuit;
a plurality of sensor output wirings;
a plurality of sensor gate signal lines;
a plurality of reset gate signal lines;
a plurality of sensor electric power source lines; and
an input pen; characterized in that:
the sensor source signal line driver circuit reads in signals from the plurality of sensor output wirings;
the sensor gate signal line driver circuit outputs signals to the plurality of sensor gate signal lines and to the plurality of reset gate signal lines;
the plurality of pixels each have an EL display portion and a sensor portion;
the EL display portion and the sensor portion are formed on the same substrate;
the sensor portion has a selection TFT, a buffer TFT, a reset TFT, and a photodiode;
a gate electrode of the selection TFT is connected to one of the plurality of sensor gate signal lines;
one of a source region and a drain region of the selection TFT is connected to one of the plurality of sensor output wirings, and the other of the source region and the drain region of the selection TFT is connected to one of a source region and a drain region of the buffer TFT;
one of the source region and the drain region of the buffer TFT, which is not connected to the selection TFT, is connected to one of the plurality of sensor electric power source lines;
a gate electrode of the buffer TFT is connected to the photodiode and to a source region or a drain region of the reset TFT;
one of the source region and the drain region of the reset TFT, which is not connected to the buffer TFT, is connected to one of the plurality of sensor electric power source lines;
a gate electrode of the reset TFT is connected to one of the plurality of the reset gate signal lines;
the EL display portion has an EL element;
light emitted by the EL element is reflected by the input pen; and
input of information is performed in accordance with the light reflected by the input pen being input to the photodiode.
In accordance with the present invention, there is provided an information device having:
a plurality of pixels;
an EL display source signal line driver circuit;
an EL display gate signal line driver circuit;
a sensor source signal line driver circuit;
a sensor gate signal line driver circuit;
a plurality of EL display source signal lines;
a plurality of EL display gate signal lines;
a plurality of electric power source supply lines;
a plurality of sensor output wirings;
a plurality of sensor gate signal lines;
a plurality of reset gate signal lines;
a plurality of sensor electric power source lines; and
an input pen; characterized in that:
the EL display source signal line driver circuit outputs signals to the plurality of EL display source signal lines;
the EL display gate signal line driver circuit outputs signals to the plurality of EL display gate signal lines;
the sensor source signal line driver circuit reads in signals from the plurality of sensor output wirings;
the sensor gate signal line driver circuit outputs signals to the plurality of sensor gate signal lines and to the plurality of reset gate signal lines;
the plurality of pixels each have an EL display portion and a sensor portion;
the EL display portion and the sensor portion are formed on the same substrate;
the EL display portion has a switching TFT, an EL driver TFT, and an EL element;
a gate electrode of the switching TFT is connected to one of the plurality of EL display gate signal lines;
one of a source region and a drain region of the switching TFT is connected to one of the plurality of EL display source signal lines, and the other of the source region and the drain region of the switching TFT is connected to a gate electrode of the EL driver TFT;
one of a source region and a drain region of the EL driver TFT is connected to one of the plurality of electric power source supply lines, and the other of the source region and the drain region of the EL driver TFT is connected to the EL element;
the sensor portion has a selection TFT, a buffer TFT, a reset TFT, and a photodiode;
a gate electrode of the selection TFT is connected to one of the plurality of sensor gate signal lines;
one of a source region and a drain region of the selection TFT is connected to one of the plurality of sensor output wirings, and the other of the source region and the drain region of the selection TFT is connected to one of a source region and a drain region of the buffer TFT;
one of the source region and the drain region of the buffer TFT, which is not connected to the selection TFT, is connected to one of the plurality of sensor electric-power source lines;
a gate electrode of the buffer TFT is connected to the photodiode and to a source region or a drain region of the reset TFT;
one of the source region and the drain region of the reset TFT, which is not connected to the buffer TFT, is connected to one of the plurality of sensor electric power source lines;
a gate electrode of the reset TFT is connected to one of the plurality of the reset gate signal lines;
light emitted by the EL element is reflected by the input pen; and
input of information is performed in accordance with the light reflected by the input pen being input to the photodiode.
The information device may also be one in which the EL display source signal line driver circuit and the EL display gate signal line driver circuit are formed on the same substrate as the EL display portion and the sensor portion.
The information device may also be one in which the sensor source signal line driver circuit and the sensor gate signal line driver circuit are formed on the same substrate as the EL display portion and the sensor portion.
The information device may also be characterized in that the EL display source signal line driver circuit, the EL display gate signal line driver circuit, the sensor source signal line driver circuit and the sensor gate signal line driver circuit are formed on the same substrate as the EL display portion and the sensor portion.
The information device may also be characterized in that the photodiode has an anode electrode, a cathode electrode, and a photoelectric conversion layer sandwiched between the anode electrode and the cathode electrode.
The information device may also be characterized in that the photoelectric conversion layer is structured by an organic material.
The information device may also be characterized in that the photodiode has a p-type semiconductor layer, an n-type semiconductor layer, and a photoelectric conversion layer sandwiched between the p-type semiconductor layer and the n-type semiconductor layer.
The information device may also be characterized in that the photoelectric conversion layer is structured by an amorphous semiconductor.
The information device may also be characterized in that:
light emitted from the EL elements is irradiated to a surface of an object;
the light irradiated to the surface of the object is reflected by the surface of the object; and
information regarding the surface of the object is input as an image in accordance with the light reflected by the surface of the object being input to the photoelectric conversion elements.
The information device may also be characterized in that information regarding the surface of the object is biological information.
The information device may also be characterized in that the biological information is a palm print.
The information device may also be characterized in that the biological information is a finger print.
The information device may also be a portable information terminal or a PDA.